Recently, light emitting devices are used for various purposes. For example, light emitting devices are used for liquid crystal display backlights, lighting for plant growth and medical lighting such as endoscopy. There are various types of light emitting devices including incandescent light bulb, fluorescent light and Light Emitting Diode (LED) lighting. Additionally, light emitting devices irradiate visible light as well as ultraviolet (UV) light. For example, Flat Panel Display (FPD) such as a liquid crystal panel or an organic Electro Luminescence (EL) panel uses UV curable resin as an adhesive. Additionally, a UV curable ink that is cured by UV irradiation is used as an ink for sheet-fed offset printing. A UV light illuminating apparatus is used to cure such a UV curable ink or UV curable resin. As above, various types of light emitting devices are used, and among them, recently, light emitting devices using LED as a light source are mainly used from the perspective of lower power consumption, a longer service life, and smaller size.
With regard to a light emitting device using LED, for example, Japanese Patent Publication No. 2010-199005 (Patent Literature 1) discloses an LED module comprising ┌first main and sub terminals for connection to an external circuit formed near the first side of the insulating substrate, second main and sub terminals for connection to an external circuit formed near the second side opposite to the first side of the insulating substrate 2, three or more connecting wires formed on the insulating substrate for connecting LEDs continuously aligned at a distance from each other in series, LEDs individually connected between the connecting wires adjacent to each other and connected in series in a same direction┘ (see ┌abstract┘).